'When you hear hoofbeats, think of horses not zebras' - the old adage is well-known to GPs but what should you do when faced with a zebra, not a horse? Consultant cardiologist Professor Robert Tulloh and GP Dr Louise Tulloh kick off our new series with their advice on how to catch Kawasaki disease in general practice.

E-cigarettes reduce chances of quitting smoking and ‘should not be recommended as smoking cessation aids’, a study published in the Lancet has claimed.

A meta-analysis of 18 previous observational studies and two clinical trials saw researchers concluding that smokers who also use e-cigarettes are significantly less likely to quit than those who only smoke conventional cigarettes.

The team from the University of California, San Francisco, deduced that use of e-cigarettes decrease a person’s chances of quitting smoking by 28%.

The paper said: ‘E-cigarette use is increasing and, although quitting smoking is a common marketing claim and is often cited as a reason for use among cigarette smokers, the overall conclusion from the available studies is that e-cigarette use is associated with reduced smoking cessation in the real world’.

Professor Paul Aveyard, a professor in behavioural medicine at the University of Oxford, said the analysis was flawed by the sample population studied.

He said: ‘This review collates many observational studies, which have particular issues in this context. Typically, they enrol people who smoke and ask them if they have used e-cigarettes.

‘The problem with the analysis is that people who were helped by e-cigarettes have left this [sample] population because they gave up smoking and therefore you leave only those who were not helped.’

Professor Robert West, a professor of health at health at University College London, went further to suggest publication of the study was ‘a major failure of the peer review system in this journal’.

Referring to an ongoing large-scale population survey of smoking in England, he said: ‘If use of e-cigarettes caused fewer smokers to quit, the quit rate in England would have decreased as use of e-cigarettes has increased. Data from the Smoking Toolkit Study shows, if anything, the opposite.

PHE director of tobacco, alcohol and drugs Rosanna O’Connor said: ‘Evidence from practice in England shows that two out of three smokers who combined e-cigarettes with additional expert support from a local stop smoking service quit successfully and while dual use is a complex issue, many vapers report using an e-cigarette to cut down and ultimately quit.’